Hi Tom Chien,
Thanks for getting back to me. In general, each version that you install should find its place in Visual Studio Toolbox. However, according to our observations, there are cases in which the Toolbox installation fails and thus no new tabs for the corresponding versions are added.
I would like to inform you that we are working on this issues but since they seem to be harder to track down and require some more time for research, we cannot give an exact timeframe when this odd behavior will be fixed.
Therefore, I would like to ask for your patience. We hope that for Q1 2010 these issues will be resolved.
the Telerik team